Paper manufacture



Patented Feb. 9, 1937 UNITED STATES PAPER MANUFACTURE Thomas a. Lecommermsbui gh, Pa., assignor to John A. Manning Paper Company, Inc.,Green Island, N. Y., a corporation of New York No Drawing. ApplicationMarch 7, 1934, Serial 19 Claims.

My invention relates to the manufacture of paper, and has for itsgeneral object improvement in the arrangement and uniformity ofdistribution of paper fibers in the formation of 5 the paper web;specific objects are: To secure good formation in papers made of longflbered stocks, such as Manila fibers, and to produce long-fiber papershaving a soft, cloth-like feel; to produce papers having lowair-resistance from hydrated stocks, and to improve the formation ofpapers made from short-flbered stocks such as sulflte and soda pulp. Theterm formation as used herein connotes the fixed disposition of thefibers of a sheet of paper and includes all effects produced in thearrangement of the fibers before the sheet passes over the drying'rolls,exclusive of marks produced by dandy rolls.

Whatever may be the character of paper making fibers, the material ofwhich they are com- 20 posed, their average length, individualpeculiarities of structure, etc., etc., uniform distribution of fibersin the web made therefrom on a paper machine is a desideratum;departures from desired or necessary uniformity of distribution 2 may bebroadly designated as flocculation, and that term is used herein assignifying the reverse of uniformity of fiber distribution in theformation of a paper web. Sundry correctives of flocculation have beenlong employed in paper manufacture, as for instance hydration ofcellulose fibers in varying degree, or the mixture with processed pulpsof varying proportions of ground wood, or the reduction of the averagefiber-length, as by a jordan, but all such measures, corrective offlocculation in paper formation, tend to produce in some measureundesirable qualities in the paper product, which would not characterizeit, if a practically perfect uniformity of arrangement and distributionof the 40 chief fiber constituent of the paper mix could be securedwithout resort to such correctives, all of which are compromisemeasures, introducting relative defects in some degree, which have to bebalanced against the advantage of uniform fiber distribution.

Probably the most striking example of fiber flocculation in papermanufacture is furnished by paper made of fibers longer than the normal,which fiocculate before and during web forma- 5 tion and do not respondto the corrective measures such as are above mentioned,.as do paperfibers of much shorter average length. Another example is supplied byWool fibers, which have a serrated structure, and have practicallydefied all attempts to make paper thereof. Also, fibers composed ofmaterial having specific gravity of pronounced difference from unity(water) so strongly tend toward flotation or sedimentation in mass as tofiocculate excessively during any attempt at paper web formation, andare therefore practically unavailable unless mixed with fibers of othermaterial which when incorporated in the paper measurably degrade thequalities it would possess in full, were the paper to' be constructed ofunadulterated fiber. Asbestos paper, in which asbestos fiber iscustomarily adulterated with vegetable-derived pulp, is a well knownexample.

Paper. fibers, of whatever nature, can be well dispersed and distributedin an abundant and well stirred body of water as the dilute mix reachesthe wet end of the paper making apparatus just prior to arrival at theweb-forming part of the same, and by the employment of the inventionherein to be described this uniform 20 dispersion of fibers is conservedduring web formation and flocculation greatly reduced, if not whollyprevented.

In an application ,for United States Letters Patent filed concurrentlyherewith and serially numbered 714,456, I have set forth and described adefiocculent gum-derivative and the method of making it. Thisgum-derivative is the defiocculant material employed by me in thepractice of the invention herein described, which comprises the methodof paper-making characterized by the use of the said gum-derivative as afiber defiocculant, and includes also the stage product in paper makingcomprising a fiber mix containing the said defiocculent dispersed in thewater, and the paper comprising fibers and the residue of saiddefiocculant left in the paper after it has become a finished product.

The defiocculent material which figures as a factor in the improvementin paper manufacture herein described, is a derivative from apolyacetylated gum, specifically the commercial gum karaya which, as setforth in the Journal of the Chemical Society; Transactions, Vol. 89, pt.2, pp. 1495 to 1505,-1906, is a tetra-acetyl derivative ofcochlosperminic acid. Gum karaya is a natural product obtained from theplant cochlospermum gossypium and allied botanical species, and ofitself when dispersed in water manifests so little defiocculating ordispersive potency as to be practically a negligible factor for suchpurposes.

Gum karaya gives physical evidence that its molecular weight is veryhigh, and its molecule very large. Though insoluble in water, it imbibes55 water and forms a jelly therewith. Two per cent. of the gum in waterforms a quite solid jelly, this jelly, however, manifests littlecoherence; it breaks short, and dispersions of low concentration showno, or feeble dispersing potency in relation to particles suspended inwater.

On treating a gum karaya dispersion in water with a mild alkali(preferably ammonia) the gum is hydrolyzed,but only to the extent ofreplacing all or part of the acetyl radicals constituent in it.Deacetylation of gum karaya produces a derivative thereof which is awater-dispersible gum (not water-soluble, as evidenced by its resistanceto filtration, which is practically the same as that of karaya Jelly)having the property of coherence in high degree and having markeddefiocculating potency.

If a dry deacetylated gum karaya is desired, it may be obtained bymixing granulated karaya with ethyl alcohol (in which the gum isinsoluble, and which causes little if any swelling of the gum) and thentreating the mixture with alcoholic ammonia, which deacteylates the gum,filtering, washing the gum with alcohol to remove ammonium acetate, anddrying. This deacetylated karaya, when dispersed in water, yieldsdispersions or jellies having the same properties as the karayaderivative produced as above described by deacetylation in water withdilute ammonia. Deacetylation can also be effected by treatinggranulated karaya with ammonia vapor.

Since commercial gum karaya is a mixture of gums collected not onlyfromthe plant Cochlospermum gossypium but from several other specificallydifferent though allied species, all of which gums respond qualitativelyalike to the action of mild alkali, and definitely undergo deacetylationin such treatment, I use the commercial term "gum karaya herein asdesignatingany poly-acetyl derivative of a gum acid or acids allied withcochlosperminic acid, having regard to the observable physicalcharacteristics of the deacetylated product rather than to a precise,(and as yet unascertained so far as I know) chemical analysis andidentification of what is probably a miscellany of gums which areevidently closely related to each other in molecular structure andcomposition.

As set forth in the said copending patent application, I have discoveredthat by treatment of gum karaya with a mild alkali, preferably diluteammonia, the gum karaya is wholly or partly deacetylated, remainingotherwise unaltered in the essentials of its nuclear molecularstructure, and that the said partly or wholly deacetylated gum karaya isa hydrophile gum derivative possessing marked coherence and-identifiableby its ability to form a coherent, stringy, tacky precipitate with ethylalcohol from a water dispersion.

To make the deacetylated derivative of karaya gum, form a jelly with twoparts by weight of the dry gum and 98 parts water. Excessive grinding ofthe gum is to be avoided, because mechanical attrition tends todegenerate it and prevent the formation of the characteristic stifljelly. Excessive mechanical agitation or stirring of the Jelly itselfhas the same tendency. The two per cent. dispersion of karaya in wateris a quite stifi jelly, which, however, breaks short", and manifests nostringiness or tackiness. To each 100 parts of this karaya jelly add 0.6part of 26 B. aqueous ammonia, or add ammonia in the same ratio to thewater in which the karaya is dispersed. The ammonia, being well mixedwith the water and dispersed gum, in from two to three hours at roomtemperature converts the gum Jelly into a deacetylated derivativethereof which M pronounced cohesion, and is stringy, fibrous, or ropy instructure. The chemical change produced by the above indicated treatmentof karaya. is deacetylation. Titration shows that the amount of ammoniaconsumed in the process is equivalent to the amount of ammonium acetateformed, and that the change is not due to formation of an ammonium saltof the gum acid, or to amination of the gum, but to deaoetylation of thekaraya; this selective hydrolysis of the karaya is accompanied by noevidence of alteration of the complex molecular nucleus of the gum.

The physical characteristics of the deacetylated I karaya derivative andthe contrast between it and karaya may be demonstrated by aprecipitation test with ethyl alcohol. If to a 2% dispersion of karayain water there be mixed an equal volume of ethyl alcohol, the gum comesdown as a fine fiocculent precipitate, whereas similar alcohol treatmentof the deacetylated karaya P oduces a tough, fibrous, stringyprecipitate.

There is good evidence that the physical characteristics of thedeacetylated but otherwise unaltered karaya are due mainly, if notwholly, to an emphatic polarity of the molecule of the gumderivative,which the molecule of the original karaya does not possess. In othercolloidal substances there may be observed the capacity to form stringsor fibers, e, g., glue and other proteins, the molecules of which haveacidic groups and basic groups in the molecule-chains. In karaya thereis a potentially active carboxyl group, and hydroxyl groups which havebeen rendered inactive by association with acetyl groups, so that themolecules are only feebly polar, if at all, and incapable of orientingthemselves. After deactylation of karaya, free and active hydroxylgroups are present, and each molecule becomes emphatically polar, havingpositive hydroxyls and negative carboxyls, and orient themselvesaccordingly. This increase in molecular polarity is shown by theelectro-conductivity of a dispersion of deacetylated karaya (washed toremove electrolytes), which is higher than that of a karaya dispersion,and is manifested by the stringy structure of the alcohol precipitates,in

' which the oriented arrangement of strongly polar molecules in thewater-dispersion persists. This behavior also indicates a stronglyprobable reason why a karaya derivative produced by hydrolyzation to theextent of 25% of the total of acetyl groups (assuming that karaya iswholly a tetra-acetyl gum-acid compolmd) is, as has been observed anddetermined, as effective a deflocculant of water-suspended paper fibersas a'more completely deacetylated derivative.

This deacetylated gum karaya manifests strong potency as a deflocculantor a disperdng agent of bodies such as fibers which are suspended inwater wherein also the said deflocculant gum derivative is colloidailyRelatively long fibers suspended in the water of a paper mix, which byreason of their length and tendency to entangle with each other and formflocks will, if the said defiocculant gum derivative be added to themix, be thereby maintained in dispersion and will, upon formation of thepaper web asupon a Fourdrinier wire or other web-'forming instrument, bedistributed thereon uniformly and without the deposition of flocks; andpaper so made will be free from the mottled appearance and irregularformation which otherwise would characterize it. Thin papers of thetissue class formedby'the depositionin the web of the lon fibersdistributed and prevented from fiocculating by the aid of the saiddeflocculant gum derivative, possess, by reason of the length of thefibers, un-' usual strength. 1

The defiocculating eificacy of the said deflocculant gum karayaderivative may easily be demonstrated in the following manner: Asuspension of relatively long fibers (e. g., Manila fibers) in water iseasily picked up by means-of a stirring rod because of the fiocculententanglement of the fibers with each other; but if a small quantity ofdeacetylated gum karaya be introduced into the water wherein thefibersare suspended, it will be found difilcult to pick up any substantialamount of the fiber by means of the stirring rod. In the case of Manilapaperfibers, a dispersion of 10% or less of the said gum (dry weight) onthe weight of the fiber in the paper mix, will be found sumcient toeffect a satisfactory defiocculation and conserved dispersion of thefibers and to render the formation of the web practically perfect.

In making paper from relatively short fibers, the contrast betweenformation with and without the above-described deflocculant gumderivative is not so striking as in the case of long-fibered paper, butthe employmentofithe said deflocculant enables the paper manufacturer todispense with the correctives of poor web-formation heretofore used, andto avoid the defects in his paper product which have heretofore beentolerated for the sake of good formation.

An example of preparation of' paper-fiber deflocculant and itsemployment in paper making, is as follows:

Disperse 100 pounds of dry karaya gum in about 5,000 pounds of water towhich 30 pounds of 26 B. ammonia has been added. Mix (avoiding violentagitation) until the dispersion is free from lumps. This dispersion,containing about 2% of gum solids, is then allowed to age for aboutthree hours, when optimum deacetylation should be complete, and is thenfurther diluted with about 35,000 pounds of water, and allowed to standat least half anhour. This dilute dispersion of karaya derivative isthen metered into the paper stock stream, preferably as near the headbox as possible. The amount is variable, according to the requirementsof different paper stocks. In general, two per cent. of thegumderivative solid on the weight of the fiber represents a maximumrequirement for any of the usual paper-making fibers. It is believed tobe preferable not to introduce this deflocculant at any point in theprogress of the stock where it would be subjected to violent agitationor mechanical attrition.

I claim:

1. Method of making paper, characterized by adding to a fiber-mix beforethe formation of a paper web therefrom, of a water-dispersiblewater-imbibing polar-molecule derivative of abefore the foi'mation of apaper web therefrom, a water dlspersible water-imbibing polar-moleculederivative of a water-imbibing non-polarmolecule gum.

5. Method of making paper, characterized by adding to a mix comprisingfibers of such character as will normally fioccuiate in paper formation,prior to the formation of a paper web therefrom, as afiber-deflocculant, water-imbibing, deacetylated, gum karaya.

6. A product, more especially for use in the manufacture of paper,comprising fibers suspended in water; and a fiber deflocculantconsisting of a water-dispersible water-imbibing polar-moleculederivative of a water-imbibing non-polar-molecule gum.

"l. A product, more especially for use' in the manufacture of paper,comprising fibers suspended in water, and a fiber deflocculantconsisting of water-imbibing partly deacetylated, gum kayara.

8. Paper comprising fibers defiocculated and distributed, andcharacterized by containing a deflocculant consisting substantially of awaterdispersible water-imbibing polar-molecule derivative of awater-imbibing non-polar-molecule gum, and the residue of saiddeflocculant.

9. Paper, comprising fibers deflocculated and distributed, andcharacterized by containing a deflocculant consisting substantially ofwaterimbibing deacetylated gum karaya, and the residue of saiddeflocculant.

10. Paper, comprising fibers defiocculated and distributed, andcharacterized by containing a deflocculant consisting substantially ofwaterimbibing partly deacetylated gum karaya, and the residue of saiddeflocculant.

11. A stage product in the manufacture of paper, comprising fiberssuspended in water, said fibers being of such length as will normallyfiocculate in paper formation, and a fiber deflocculant consisting of awater-imbibing deacetylated, gum karaya.

12. A stage product in the manufacture of paper, comprising fiberssuspended in water, said I fibers being of such length as will normallyflocculate in paper formation, and a fiber deflocculant consisting ofwater-imbibing, partly deacetylated, gum karaya.

13. Paper, comprising fibers of such length as will normally fiocculatein paper formation, defiocculated and distributed by means of adeflocculant consisting of water-imbibing deacetylated gum karaya, andthe residue of said deflocculant.

14. Paper, comprising fibers of such length as will normally fiocculatein paper formation, defiocculated and distributed by means of adeflocculant consisting of water-imbibing, partly deacetylated gumkaraya, and the residue of said deflocculant. 7

15. A product more especially for use inthe manufacture of paper,comprising fibers suspended in water, and a fiber deflocculant ofwater-imbibing, deacetylated gum karaya.

16. A product more especially for use in the manufacture of paper,comprising fibers suspended in water, and a fiber deflocculant ofwater-imbibing, partly deacetylated gum karaya.

17. Method of making a felted fibrous structure, from an aqueoussuspension of fibers, which comprises adding to the fibrous suspension,before formation of the felted structure therefrom, water-imbibing,partially deacetylated gum karaya.

4 18. Method of making a felted fibrous structure, from an aqueoussuspension of fibers, which comprises adding to the fibrous suspension,before formation of the felted structure therefrom,

b water-imbibing deacetylated gum karaya.

19. A stage product in the manufacture of a felted fibrous strucconi'prising a'wat'r suspension of flbers,'f's aid;iiber'sbeing of'suchlength as would normaIly-floccuia-tfignd a; fiber deflocculantconsisting substentiallyof water-imbibing deacetyiated sum kareyai' Q

